Herbicidally active substituted phenoxy benzoxazole (or benzothiazole)

ABSTRACT

This invention relates to herbicidally active substituted benzoxazole (or benzothiazole) compounds and to the use of such compounds to control the growth of noxious plants, i.e., weeds.

FIELD OF THE INVENTION

This invention relates to herbicidally active substituted benzoxazole(or benzothiazole) compounds and to the use of such compounds to controlthe growth of noxious plants, i.e., weeds.

DESCRIPTION OF THE INVENTION

This invention provides herbicidally active substituted benzoxazole (orbenzothiazole) compounds represented by the Formula I. ##STR1## whereinAr is ##STR2## wherein: W is oxygen, S(O)_(x) or NR⁹ wherein X is 0, 1or 2 and R⁹ is hydrogen or C₁ to C₄ alkyl;

W¹ and W² are independently oxygen or S(O)_(x) ;

W³ is oxygen or S(O)_(x) ;

X is CY, N, N.sup.⊕ --O.sup.⊖ or N.sup.⊕ --CH₃ ;

Q is N or N.sup.⊕ --O.sup.⊖ ;

Z is CH or N;

Y is hydrogen, halogen, cyano, nitro or lower haloalkyl;

Y¹ and Y² are independently hydrogen, halogen, nitro, cyano or loweralkyl, haloalkyl, alkoxy, alkoxyalkyl or alkyl sulfonyl;

Y³ is hydrogen, halogen, cyano, nitro or lower haloalkyl and n is 0, 1,2 or 3;

R is ##STR3## wherein R¹ is hydrogen, halogen, nitro, cyano, C₁ to C₄alkyl, haloalkyl, cycloalkyl, alkoxy or substituted alkoxy, alkoxyalkyl,carboxy, carboalkoxy, Ar, Ar--W, Ar--R⁴ or Ar--R⁴ --W wherein R⁴ is C₁to C₄ alkylene;

R² is hydrogen, halogen or C₁ to C₄ alkyl;

R³ is up to C₃ alkylene, alkenyl or alkynyl which may be mono ordisubstituted by a member or members selected from R¹ ;

p is 0 or 1;

B is hydrogen, C₁ to C₆ alkyl or haloalkyl, dialkylphosphonyl, --OR⁵,--SR⁵ or --NR⁶ R⁷ wherein:

R⁵ is hydrogen, alkali metal, ammonium or substituted ammonium, C₁ to C₆alkyl, haloalkyl, oxoalkyl, hydroxyalkyl, thioalkyl, alkoxyalkyl,cycloalkyl, alkylene-S(O)_(x) -alkyl, alkenyl or alkynyl, alkoxycarbonylalkyl including amides and salts thereof, trialkylammonium alkyl,dialkylphosphonyl alkyl, Ar¹ -(R⁸)_(y) -wherein R⁸ is C₁ to C₄ alkylene,y is 0 or 1 and Ar¹ is substituted or unsubstituted phenyl or pyridyl,or R⁵ is a 5 to 6 membered heterocyclic ring containing up to 3 heteroatoms;

R⁶ and R⁷ are independently hydrogen, C₁ to C₆ alkyl, alkoxy,alkoxyalkyl, alkylaminoalkyl, alkylsulfonyl, dialkylphosphonyl alkyl,alkylene-S(O)_(x) -alkyl, alkenyl or alkynyl or R⁶ and R⁷ may combine toform a 5 to 6 membered heterocyclic ring containing up to 3 heteroatoms; and

L is oxygen or sulfur when B is --OR⁵, --SR⁵ or --NR⁶ R⁷ ; but when B ishydrogen, alkyl or alkoxy L may also be dialkoxy or dioxyalkylene.

Although any herbicidally active compound within the scope of Formula Iis contemplated by this invention, some preferred compounds are thoserepresented by Formula II: ##STR4## wherein X, Y¹, Y², Y³, W, W¹, R andn are as previously defined.

Most preferred compounds are those Formula II compounds wherein Y¹ is a2-halogen, e.g., chlorine, bromine or fluorine; Y² is a 4-lowerhaloalkyl, e.g., trifluoromethyl; X is CY wherein Y is hydrogen orhalogen, e.g., chlorine or fluorine, W and W¹ are oxygen, n is 0 and Ris ##STR5## wherein R¹¹ and R¹² are independently hydrogen or C₁ to C₄alkyl and R¹⁰ is C₁ to C₄ alkyl.

Also preferred is the 5-(aryloxy)-benzoxazole isomer. Of course, thestereo isomers of the Formula I compounds are within the scope of thisinvention.

The compounds of the invention may be readily synthesized using methodsknown to the art. For example, certain of the Formula I compounds, i.e.,those wherein may be prepared by reacting a suitably substitutedaminophenol of the Formula III: ##STR6## wherein Ar, W and Y³ _(n) areas previously defined with carbon disulfide and potassium hydroxide inalcohol to form a benzoxazolethione of the Formula IV: ##STR7##

The Formula IV compound is then alkylated with a suitably substitutedhalogenated compound of the Formula V. ##STR8## wherein Hal is halogen,e.g., bromine or chlorine, and R¹, R², R³, p, L and B are as previouslydefined to form a compound of the invention.

The preparation of certain specific compounds of the invention areillustrated by the following Examples:

EXAMPLE I Preparation of:5-(2-chloro-4-trifluoromethylphenoxy)-2-carbomethoxymethylthiobenzoxazole

A mixture of 1.73 grams (0.005 mole) of5-(2-chloro-4-trifluoromethylphenoxy)benzoxazolethione, 20 millilitersof dimethylformamide and 1.56 grams (0.01 mole) of methyl bromoacetatewas alternately stirred at room temperature and at moderate elevatedtemperature (43°-48° C.) over a period of several days, the progress ofthe reaction monitored by HPLC analysis. Upon completion of thereaction, solvent was evaporated at reduced pressure, the residue wasdissolved in methylene chloride and thrice extracted with water. Theorganic layer was dried over anhydrous magnesium sulfate and solvent wasevaporated at reduced pressure. The crude material was further purifiedby column chromatography using methylene chloride as the eluent,affording 0.85 grams of material identified by GC and MS analysis as thedesired product.

EXAMPLE II Preparation of:5-(2-chloro-4-trifluoromethylphenoxy)-2-(1-carbomethoxy)ethylthiobenzoxazole

A mixture of 1.73 grams (0.005 mole) of5-(2-chloro-4-trifluoromethylphenoxy)benzoxazolethione, 1.00 gram (0.006mole) of methyl 2-bromopropionate, 1.40 grams (0.01 mole) of potassiumcarbonate and 15.66 grams of dimethyl formamide was stirred at roomtemperature for about 24 hours, the progress of the reaction monitoredby HPLC analysis. Solvent was then evaporated under reduced pressure,the residue was dissolved in methylene chloride and extracted twice withwater. The organic layer was dried over anhydrous magnesium sulfate andsolvent was evaporated at reduced pressure. The crude material wasfurther purified by column chromatography using methylene chloride asthe eluent, affording 1.53 grams of material confirmed by MS and HPLCanalyses as the desired product.

The compounds prepared in the foregoing Examples I and II arerepresented by the following Formula VI: ##STR9## wherein R is asfollows:

    ______________________________________                                        Example     R                                                                 ______________________________________                                        I           --CH.sub.2 COOCH.sub.3                                            II          --CH(CH.sub.3)COOCH.sub.3                                         ______________________________________                                    

Although the invention has been illustrated by the foregoing Exampleswith regard to the preparation of specific compounds within the scope ofFormula I, it is to be understood that all of other compounds within thescope of Formula I may readily be prepared by those skilled in the artby varying the choice of starting materials and using the same orsimilar techniques.

Weed control in accordance with this invention is effected by applyingto the soil before emergence of weeds therefrom or to the plant after anemergence from the soil, a herbicidally effective amount of a compoundof this invention. It is, or course, to be understood that the term "acompound of this invention" also includes mixtures of such compounds.

The term "herbicidally effective amount" is that amount of a compound ofthis invention required to so injure or damage weeds such that the weedsare incapable of recovering following application while not causingsubstantial injury to valuable crops amongst which the weeds might begrowing. The quantity of a compound of this invention applied in orderto exhibit a satisfactory herbicidal effect may vary over a wide rangeand depends on a variety of factors, such as, for example, hardiness ofa particular weed species, extent of weed infestation, climaticconditions, soil conditions, method of application, and the like. Ofcourse, the efficacy of a particular compound against a particular weedspecies may readily be determined by routine laboratory or field testingin a manner well known to the art. It is expected that satisfactorypostemergence weed control can be had at a rate of application in therange of 0.0001 to 10 pounds per acre, and typically in the range of0.01 to 5.0 pounds per acre.

Of course, a compound of this invention can be formulated according toroutine methods with any of several known and commonly used herbicidaldiluents, adjuvants and carriers. The formulations can contain liquidcarriers and adjuvants such as organic solvents, as well as emulsifiers,stabilizers, dispersants, suspending agents, spreaders, penetrants,wetting agents and the like. Typical carriers utilized in dryformulations include clay, talc, diatomaceous earth, silica and thelike. Preferred formulations are those in the form of wettable powders,flowables, dispersible granulates or aqueous emulsifiable concentrateswhich can be diluted with water at the site of application. Also, dryformulations such as granules, dusts, and the like, may be used.

When desired, a compound of this invention can be applied in combinationwith other herbicidal agents in an effort to achieve even broadervegetative control. Typical herbicides which can be convenientlycombined with Formula I compound include atrazine, hexazinone,metribuzin, ametryn, cyanazine, cyprazine, prometon, prometryn,propazine, simazine, terbutryn, propham, alachlor, acifluorfen,bentazon, metolachlor and N,N-dialkyl thiocarbamates such as EPTC,butylate or vernolate. These, as well as other herbicides described, forexample, in the Herbicide Handbook of the Weed Science Society ofAmerica may be used in combination with a compound or compounds of theinvention. Typically such formulations will contain from about 5 to 95percent by weight of a compound of this invention.

The herbicidal formulations contemplated herein can be applied by any ofseveral methods known to the art. Generally, the formulation will beapplied as an aqueous spray. Such application can be carried out byconventional ground equipment, or if desired, the sprays can be aeriallyapplied. Soil incorporation of such surface applied herbicides isaccomplished by natural leaching, and is of course facilitated bynatural rainfall and melting snow. If desired, however, the herbicidescan be incorporated into the soil by conventional tillage means.

Compounds of this invention are effective for preemergence control andparticularly for postemergence control of a wide variety of broadleafand grassy weeds. Typical of the various species of vegetative growththat may be controlled, combated, or eliminated are, for example,annuals such as pigweed, lambsquarters, foxtail, crabgrass, wildmustard, field pennycress, ryegrass, goose grass, chickweed, wild oats,velvetleaf, purslane, barnyardgrass, smartweed, knotweed, cocklebur,kochia, medic, ragweed, hemp, nettle, spurrey, pondweed, carpetweed,morningglory, ducksalad, cheatgrass, fall panicum, jimsonweed,witchgrass, watergrass, wild turnip, and similar annual grasses andweeds. Biennials that may be controlled include wild barley, campion,burdock, bull thistle, roundleaved mallow, purple star thistle, and thelike. Perennials such as quackgrass, Johnsongrass, Canada thistle,curley dock, field chickweed, dandelion, Russian knapweed aster,horsetail ironweed, seabania, cattail, wintercress, horsenettle,nutsedge, milkweed, sicklepod, and the like may also be controlled byapplication of the compounds of this invention.

For example, the compounds prepared in the Examples were tested forpostemergence herbicidal efficacy, against a variety of broadleaf weedspecies, under controlled laboratory conditions of light, humidity andtemperature. A solvent solution of each compound was applied to testflats containing the various weed species, and herbicidal efficacy wasdetermined by visual inspection, periodically after application of thecompounds. Herbicidal efficacy was determined on a Numerical InjuryRating (NIR) scale of from 0 (no injury) to 10 (all plants dead). A NIRrating of 7 to 9 indicates severe injury; a NIR rating of 4 to 6indicates moderate injury, i.e., plant growth is reduced to the extentthat normal growth would be expected only under ideal conditions; and aNIR rating of 1 to 3 indicates slight injury.

The following table gives the average postemergence NIR for each of thecompounds of Examples I and II against the broadleaf weed species towhich the compounds were applied at a rate of application of 1.0 poundper acre. The NIR was determined two weeks after application. Thebroadleaf weeds used in the tests were coffeeweed (COFE), jimsonweed(JMWD), tall morningglory (MNGY), teaweed (TEAW), velvetleaf (VTLF),sicklepod (SKPD) and lambsquarters (LMBQ).

    ______________________________________                                        Postemergence NIR                                                                            I    II                                                        ______________________________________                                        COFE             5      10                                                    JMWD             9      10                                                    MNGY             10     10                                                    TEAW             6       9                                                    VLTF             6      10                                                    SKPD             1       2                                                    LMBQ             9      10                                                    ______________________________________                                    

Although the invention has been described in considerable detail by theforegoing, it is to be understood that many variations may be madetherein by those skilled in the art without departing from the spiritand scope thereof as defined by the appended claims.

What is claimed is:
 1. A compound of the formula: ##STR10## Y and Y¹ areindependently hydrogen or halogen; X and W are independently oxygen orsulfur; andR¹⁰, R¹¹ and R¹² are independently hydrogen or C₁ to C₄alkyl.
 2. A compound of claim 1 wherein Y¹ is chlorine or fluorine and Yis hydrogen, chlorine, bromine or fluorine.
 3. A herbicidal formulationcontaining an inert carrier and a herbicidally effective amount of acompound or mixture of compounds defined by claims 1 or
 2. 4. In amethod of controlling weeds growth wherein a herbicidally effectiveamount of herbicide is applied to the situs of the weeds, theimprovement residing in using as the herbicide a compound or mixture ofcompounds defined by claims 1 or 2.